Hedgerow Shading Reduces Heat Stress and Improves Cacao Physiology and Soil Fertility in Tropical Systems

Abstract Aims Elevated temperatures during the vegetative phase pose a significant threat to the physiological stability and growth of cacao (Theobroma cacao L.), particularly on limited land in tropical areas. This study examined the efficacy of vegetation-based hedgerow shading for enhancing cacao performance under extreme heat stress conditions. Methods Field experiments were conducted in South Sulawesi, Indonesia, using three levels of natural shade intensity (0–25%, 25–50%, and 50–75%), quantified via aerial imaging. The hedgerow system utilized native multipurpose species arranged in layered canopies to regulate microclimate and soil characteristics. Key physiological (chlorophyll concentration and light penetration) and edaphic parameters (nitrogen availability, carbon-to-nitrogen (C/N) ratio, and cation exchange capacity) were measured along with vegetative growth traits. Results The 50–75% shading treatment yielded the most favorable physiological and agronomic outcomes. This condition improved the chlorophyll concentration, light distribution, and nitrogen content, while reducing the C/N ratio and increasing cation exchange capacity. Vegetative cacao growth under this treatment showed significantly greater height (247.5 cm), stem diameter (7.8 cm), and canopy width (223.6 cm) than under the other shade levels. Conclusions This hedegrow system is an agroecological strategy that provides a sustainable approach for climate-resilient cacao cultivation in tropical regions vulnerable to extreme temperatures.